Capacitive vacuum sensor

Abstract

A capacitive vacuum sensor includes a non-conducting substrate, a plurality of fixed electrodes on the non-conducting substrate, and a diaphragm electrode formed by a plurality of elastic structures, each of the elastic structures being arranged to oppose a respective one of the fixed electrodes and having a different physical size (area) that is the same as that of each corresponding fixed electrode. More specifically, the areas of the elastic structures have a specific relationship between them, as defined by a specific ratio, and the areas may differ successively from each other according to the specific ratio. The capacitive vacuum sensor further includes compensation electrodes that are not sensitive to any change in the capacitance that may occur in response to any change in the pressure, but is only sensitive to any change in the capacitance that may occur in response to any change in the temperature. The elastic structures forming the diaphragm electrode have a plurality of projections on the surfaces to detach the elastic structures, which have been pressed against by the corresponding fixed electrodes under the higher pressure, away from the corresponding fixed electrodes when the pressure becomes lower.

What is claimed is:  
     
       1. A capacitive vacuum sensor for providing electrical information to an electrical circuit in response to pressure exerted by a gas, said capacitive vacuum sensor comprising: 
       a rigid structure comprising a diaphragm electrode portion having a plurality of elastic portions and a rigid portion for supporting said plurality of elastic portions, each of said plurality of elastic portions having an area that is different than the remaining elastic portions, each of said elastic portions arranged so as to contact the gas, each of said elastic portions being capable of deforming a deformation amount that is proportional to its area in response to a pressure exerted by the gas, each area of said elastic portions differs from the remaining areas of said elastic portions such that each respective deformation amount differs successively;  
       a non-conducting substrate arranged to oppose said rigid structure such that a space is disposed between said non-conducting substrate and said rigid structure;  
       a plurality of fixed electrodes disposed on a side of said non-conducting substrate, the number of fixed electrodes in said plurality of fixed electrodes is equal to the number of elastic portions in said plurality of elastic portions, each of said fixed electrodes is disposed so as to oppose a respective one of said elastic portions, each of said fixed electrodes having an area equal to the area of said respective one of said elastic portions, whereby a change in capacitance between each fixed electrode and respective elastic portion in response to a deformation of said respective elastic portion in accordance with the pressure exerted by the gas provides electrical information to an electrical circuit such that the pressure of the gas is determined from the electrical information; and  
       a plurality of compensating electrodes disposed on said non-conducting substrate, each of said compensating electrodes being disposed adjacent a respective one of said fixed electrodes so as to oppose said rigid portion, each of said compensating electrodes having an area equal to the area of said respective one of said fixed electrodes.  
     
     
       2. The capacitive vacuum sensor of  claim 1 , further comprising a nonevaparable getter, 
       wherein the space disposed between said non-conducting substrate and said rigid structure comprises a single closed space,  
       wherein said non-conducting substrate has a slit formed thereon for communicating with the single closed space, and  
       wherein said nonevaparable getter is disposed in the single closed space.  
     
     
       3. The capacitive vacuum sensor of  claim 2 , wherein each of said plurality of elastic portions has a plurality of projections on a surface thereof that opposes each corresponding one of said plurality of fixed electrodes. 
     
     
       4. The capacitive vacuum sensor of  claim 3 , further comprising electrically conducting leads passing through said non-conducting substrate, 
       wherein each said lead is capable of providing an electrical connection between said side of said non-conducting substrate and another side of said non-conducting substrate, and  
       wherein each said area of said elastic portions differs from the remaining areas of said elastic portions such that each respective amount of deformation differs successively by a ratio between 15 and 70.  
     
     
       5. The capacitive vacuum sensor of  claim 2 , further comprising electrically conducting leads passing through said non-conducting substrate, 
       wherein each said lead is capable of providing an electrical connection between said side of said non-conducting substrate and another side of said non-conducting substrate.  
     
     
       6. The capacitive vacuum sensor of  claim 2 , wherein each said area of said elastic portions differs from the remaining areas of said elastic portions such that each respective amount of deformation differs successively by a ratio between 15 and 70. 
     
     
       7. The capacitive vacuum sensor of  claim 1 , wherein each of said plurality of elastic portions has a plurality of projections on a surface thereof that opposes each corresponding one of said plurality of fixed electrodes. 
     
     
       8. The capacitive vacuum sensor of  claim 7 , further comprising electrically conducting leads passing through said non-conducting substrate, 
       wherein each said lead is capable of providing an electrical connection between said side of said non-conducting substrate and another side of said non-conducting substrate.  
     
     
       9. The capacitive vacuum sensor of  claim 7 , wherein each said area of said elastic portions differs from the remaining areas of said elastic portions such that each respective amount of deformation differs successively by a ratio between 15 and 70. 
     
     
       10. The capacitive vacuum sensor of  claim 1 , further comprising electrically conducting leads passing through said non-conducting substrate, 
       wherein each said lead is capable of providing an electrical connection between said side of said non-conducting substrate and another side of said non-conducting substrate.  
     
     
       11. The capacitive vacuum sensor of  claim 10 , wherein each said area of said elastic portions differs from the remaining areas of said elastic portions such that each respective amount of deformation differs successively by a ratio between 15 and 70. 
     
     
       12. The capacitive vacuum sensor of claims  1 , wherein each said area of said elastic portions differs from the remaining areas of said elastic portions such that each respective amount of deformation differs successively by a ratio between 15 and 70. 
     
     
       13. A capacitive vacuum sensor for providing electrical information to an electrical circuit in response to pressure exerted by a gas, said capacitive vacuum sensor comprising: 
       a rigid structure comprising a diaphragm electrode portion having a plurality of elastic portions and a rigid portion for supporting said plurality of elastic portions, each of said plurality of elastic portions having an area that is different than the remaining elastic portions, each of said elastic portions arranged so as to contact the gas, each of said elastic portions being capable of deforming a deformation amount that is proportional to its area in response to a pressure exerted by the gas, each area of said elastic portions differs from the remaining areas of said elastic portions such that each respective deformation amount differs successively;  
       a non-conducting substrate arranged to oppose said rigid structure such that a single closed space is disposed between said non-conducting substrate and said rigid structure; and  
       a plurality of fixed electrodes disposed on a side of said non-conducting substrate, the number of fixed electrodes in said plurality of fixed electrodes is equal to the number of elastic portions in said plurality of elastic portions, each of said fixed electrodes is disposed so as to oppose a respective one of said elastic portions, each of said fixed electrodes having an area equal to the area of said respective one of said elastic portions, whereby a change in capacitance between each fixed electrode and respective elastic portion in response to a deformation of said respective elastic portion in accordance with the pressure exerted by the gas provides electrical information to an electrical circuit such that the pressure of the gas is determined from the electrical information; and further consisting  
       a nonevaparable getter disposed in the single closed space,  
       wherein said non-conducting substrate has a slit formed thereon for communicating with the single closed space.  
     
     
       14. The capacitive vacuum sensor of  claim 13 , further comprising a plurality of compensating electrodes disposed on said non-conducting substrate, each of said compensating electrodes being disposed adjacent a respective one of said fixed electrodes so as to oppose said rigid portion, each of said compensating electrodes having an area equal to the area of said respective one of said fixed electrodes. 
     
     
       15. The capacitive vacuum sensor of  claim 13 , wherein each of said plurality of elastic portions has a plurality of projections on a surface thereof that opposes each corresponding one of said plurality of fixed electrodes. 
     
     
       16. The capacitive vacuum sensor of  claim 13 , further comprising electrically conducting leads passing through said non-conducting substrate, 
       wherein each said lead is capable of providing an electrical connection between said side of said non-conducting substrate and another side of said non-conducting substrate.  
     
     
       17. The capacitive vacuum sensor of claims  13 , wherein each said area of said elastic portions differs from the remaining areas of said elastic portions such that each respective amount of deformation differs successively by a ratio between 15 and 70. 
     
     
       18. A capacitive vacuum sensor for providing electrical information to an electrical circuit in response to pressure exerted by a gas, said capacitive vacuum sensor comprising: 
       a rigid structure comprising a diaphragm electrode portion having a plurality of elastic portions and a rigid portion for supporting said plurality of elastic portions, each of said plurality of elastic portions having an area that is different than the remaining elastic portions, each of said elastic portions arranged so as to contact the gas, each of said elastic portions being capable of deforming a deformation amount that is proportional to its area in response to a pressure exerted by the gas, each area of said elastic portions differs from the remaining areas of said elastic portions such that each respective deformation amount differs successively;  
       a non-conducting substrate arranged to oppose said rigid structure such that a space is disposed between said non-conducting substrate and said rigid structure;  
       a plurality of fixed electrodes disposed on a side of said non-conducting substrate, the number of fixed electrodes in said plurality of fixed electrodes is equal to the number of elastic portions in said plurality of elastic portions, each of said fixed electrodes is disposed so as to oppose a respective one of said elastic portions, each of said fixed electrodes having an area equal to the area of said respective one of said elastic portions, whereby a change in capacitance between each fixed electrode and respective elastic portion in response to a deformation of said respective elastic portion in accordance with the pressure exerted by the gas provides electrical information to an electrical circuit such that the pressure of the gas is determined from the electrical information; and  
       electrically conducting leads passing through said non-conducting substrate,  
       wherein each said lead is capable of providing an electrical connection between said side of said non-conducting substrate and another side of said non-conducting substrate.  
     
     
       19. The capacitive vacuum sensor of  claim 18 , further comprising a nonevaparable getter, 
       wherein the space disposed between said non-conducting substrate and said rigid structure comprises a single closed space,  
       wherein said non-conducting substrate has a slit formed thereon for communicating with the single closed space, and  
       wherein said nonevaparable getter is disposed in the single closed space.  
     
     
       20. The capacitive vacuum sensor of  claim 18 , wherein each of said plurality of elastic portions has a plurality of projections on a surface thereof that opposes each corresponding one of said plurality of fixed electrodes. 
     
     
       21. The capacitive vacuum sensor of  claim 18 , wherein each said area of said elastic portions differs from the remaining areas of said elastic portions such that each respective amount of deformation differs successively by a ratio between 15 and 70.